2010 UY points can only be banked into your 2011 UY. However, depending on what the actual UY is will determine whether any of those banked 2010 points can be used for a trip in 2012.
The points needed for trips are based on the UY that the trip will happen. In your case, a February 2012 trip will take place in your March 2011 UY (or April, June, etc--whatever you ask to get it changed to).
Since the TRIP falls in the 2011 UY, those 2010 points are available. Trips in your 2011 UY can use banked 2010 points, 2011 points, and borrowed 2012 points.
The easiest way, IMO, to figure this stuff out is to first write down what UY your travel will take place. Once that is known, you can always use banked points from the prior UY, current UY points, and borrowed UY points from the next one. It is all about the time of travel.
A UY runs from the 1st day of the month you have until the last day of the month prior. So, an April UY goest April 1st through March 31st. A June UY (there is no May) goest June 1st through May 31st.
Hope this helps!